||There has been considerable growth in the use of soil-reinforcement in geotechnical construction during the past ten years. With the huge construction activities currently in progress, soil-reinforcement technology is and will be in great demand in Hong Kong. The increasing use of soil-reinforcement has stimulated much research on the interaction of geosynthetics with soil. However, the overall picture of the interface behaviours is still as unclear as ever due to the lack of a testing device that can adequately describe the in-situ soil-reinforcement interaction. In this study, soil-reinforcement interaction, determined by a new technique using a new testing apparatus will be presented. The testing apparatus is essentially a triaxial cell fitted with the capability to accommodate a hollow cylindrical sand specimen and a concentric layer of reinforcing material sandwiched in the middle. The reinforcement is fastened at the base. The hollow specimen can be viewed as a "unit sheet" of a soil-reinforcement composite system of infinite horizontal extent. This testing device has the capability to properly simulate the in-situ loading and boundary conditions under both short and long term testing conditions. Three kinds of geotextiles, with different frictional and stiffness properties, were employed in this study. Under the simulated in-situ conditions established by the new apparatus, the stress-strain-strength behaviours of the geotextiles were found to be dependent upon the frictional and stiffness behaviours of the geotextiles, but the overall behaviours of the reinforced soils were significantly affected by the damage of surface textures of geotextiles during shear loading. A proposed failure mechanism on soil-reinforcement interface is given in the present study.